Challenger 2000 is a rulebook focusing on modern warfare from 1970 up to 1995. It is at 6mm (1:300) scale and focuses on battle groups (company level). It introduces rules for new weapons and equipment, such as Explosive Reactive Armour, modified missiles to deal with it, countermeasures (including anti-missile systems) and sensors.Major changes from Challenger II to Challenger 2000 include: a) A new move sequence. b) Area fire is treated as a combined firefight rather than a number of individual elements firing. c) A new morale system based on sub-units. - BoardGameGeek